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961.
Alexander E.Braun 《集成电路应用》2006,(5):25-25
涉足尖端技术研究工作的芯片制造商正在把无数新材料和奇特的器件结构结合起来,用于65nm及更低节点的量产。同时他们发现,在这些研究上的努力生产的结果还包括目前必须着手解决各器件各个层上出现的 相似文献
962.
Eugne T. W. M. Schipper Alexander H. C. Roelofs Pieter Piet Anton L. German 《Polymer International》1994,33(1):79-86
In order to study the promoting effect of polycations on the cobalt(II)phthalocyanine-tetrasodiumsulphonate (CoPc(NaSO3)4)-catalysed autoxidation of thiols, it is imperative to know the molecular weight dependence of the polymer. Monodisperse oligomers can often supply a lot of information. To elecidate the mechanism of the promoting effect of 2,4-ionene, a poly(quaternary ammonium)salt, on the CoPc(NaSO3)4-catalysed autoxidation of 2-mercaptoethanol, a series of monodisperse 2,4-ionene oligomers were prepared. Trimeric 2,4-ionenes, containing two quaternary ammonium groups separated by four methylene groups, showed a high co-catalytic activity, and active Co-aggregates were detected with visible light spectroscopy. The spectroscopic behaviour was in close agreement with that of high molecular 2,4-ionene/CoPc(NaSO3)4 complexes. In order to achieve this aggregation several oligomeric ionenes have to act concertedly. If the distance between the ionic sites is short the trimer acts as a simple salt in stablizing the aggregates. With respect to the catalytic activity the optimum polycation/catalyst ratio, expressed as the N+/Co ratio, decreased with increasing chain lenght and reached a constant level of 50 at a 2,4-ionene nonamer. For the trimers and pentamers this ratio is affected by the type of end-group. All synthesized 2,4-ionene oligomers exhibited excellent co-catalytic properties at the optimum N+/Co ratio, with maximum turnover frequencies of 4600 mol thiol/(mol Co s), i.e. 50 times higher than those obtained for the polymer-free system. In the case of monodisperse 2,4-ionene pentamer with bromo end-groups, double Michaelis–Menten kinetics were observed, as also was exhibited by high molecular weight ionene. 相似文献
963.
964.
Alexander Silverman 《Journal of the American Ceramic Society》1924,7(11):795-802
A discussion of the various elements and compounds found in a colloidal state in glass. Attention is called to the similarity of colloidal behavior in vitreous and aqueous media. Theories and experimental evidence are furnished to account for the formation and destruction of the colloidal state. 相似文献
965.
966.
967.
Marcus May Sandor Batkai Alexander A. Z?rner Dimitrios Tsikas Jens Jordan Stefan Engeli 《International journal of molecular sciences》2014,15(1):1189-1200
Circulating asymmetrical dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthesis, has been proposed as a biomarker for clinical outcome. Dimethylarginine dimethylaminohydrolase (DDAH) is the main enzyme responsible for ADMA metabolism and elimination. Adipose tissue ADMA concentrations and DDAH activity and their role in diabetes and obesity have not yet been investigated. In this study, we evaluated clinical microdialysis in combination with a sensitive analytical method (GC-MS/MS) to measure ADMA concentrations in extracellular fluid. Adipose tissue ADMA concentrations were assessed before and during an oral glucose tolerance test in lean healthy subjects and subjects with diabetes (n = 4 each), and in morbidly obese subjects before and after weight loss of 30 kg (n = 7). DDAH activity was determined in subcutaneous and visceral adipose tissue obtained during laparoscopic surgery (n = 5 paired samples). Mean interstitial ADMA concentrations did not differ between study populations (healthy 0.17 ± 0.03 μM; diabetic 0.21 ± 0.03 μM; morbidly obese 0.16 ± 0.01 and 0.17 ± 0.01 μM before and after weight loss, respectively). We did not observe any response of interstitial ADMA concentrations to the oral glucose challenge. Adipose tissue DDAH activity was negligible compared to liver tissue. Thus, adipose tissue ADMA plays a minor role in NO-dependent regulation of adipose tissue blood flow and metabolism. 相似文献
968.
Dr. Alexander A. Aksenov Christian E. Sandrock Dr. Weixiang Zhao Shankar Sankaran Michael Schivo Richart Harper Dr. Carol J. Cardona Dr. Zheng Xing Dr. Cristina E. Davis 《Chembiochem : a European journal of chemical biology》2014,15(7):1040-1048
Volatile organic compounds (VOCs) emanating from humans have the potential to revolutionize non‐invasive diagnostics. Yet, little is known about how these compounds are generated by complex biological systems, and even less is known about how these compounds are reflective of a particular physiological state. In this proof‐of‐concept study, we examined VOCs produced directly at the cellular level from B lymphoblastoid cells upon infection with three live influenza virus subtypes: H9N2 (avian), H6N2 (avian), and H1N1 (human). Using a single cell line helped to alleviate some of the complexity and variability when studying VOC production by an entire organism, and it allowed us to discern marked differences in VOC production upon infection of the cells. The patterns of VOCs produced in response to infection were unique for each virus subtype, while several other non‐specific VOCs were produced after infections with all three strains. Also, there was a specific time course of VOC release post infection. Among emitted VOCs, production of esters and other oxygenated compounds was particularly notable, and these may be attributed to increased oxidative stress resulting from infection. Elucidating VOC signatures that result from the host cells response to infection may yield an avenue for non‐invasive diagnostics and therapy of influenza and other viral infections. 相似文献
969.
Surin K. Mong Alexander A. Vinogradov Mark D. Simon Prof. Bradley L. Pentelute 《Chembiochem : a European journal of chemical biology》2014,15(5):721-733
We report the convergent total synthesis of two proteins: DARPin pE59 and Bacillus amyloliquefaciens RNase (Barnase). Leveraging our recently developed fast‐flow peptide‐synthesis platform, we rapidly explored numerous conditions for the assembly of long polypeptides, and were able to mitigate common side reactions, including deletion and aspartimide products. We report general strategies for improving the synthetic quality of difficult peptide sequences with our system. High‐quality protein fragments produced under optimal synthetic conditions were subjected to convergent native chemical ligation, which afforded native full‐length proteins after a final desulfurization step. Both DARPin and Barnase were folded and found to be as active as their recombinant analogues. 相似文献
970.
George M. Burslem Hannah F. Kyle Dr. Alexander L. Breeze Dr. Thomas A. Edwards Prof. Adam Nelson Dr. Stuart L. Warriner Prof. Andrew J. Wilson 《Chembiochem : a European journal of chemical biology》2014,15(8):1083-1087
The therapeutically relevant hypoxia inducible factor HIF‐1α–p300 protein–protein interaction can be orthosterically inhibited with α‐helix mimetics based on an oligoamide scaffold that recapitulates essential features of the C‐terminal helix of the HIF‐1α C‐TAD (C‐terminal transactivation domain). Preliminary SAR studies demonstrated the important role of side‐chain size and hydrophobicity/hydrophilicity in determining potency. These small molecules represent the first biophysically characterised HIF‐1α–p300 PPI inhibitors and the first examples of small‐molecule aromatic oligoamide helix mimetics to be shown to have a selective binding profile. Although the compounds were less potent than HIF‐1α, the result is still remarkable in that the mimetic reproduces only three residues from the 42‐residue HIF‐1α C‐TAD from which it is derived. 相似文献